Stabilizer composition containing more than 20% tin and resin compositions containing the same

ABSTRACT

A POLYVINYL CHORIDE RESIN STABILIZER IS PROVIDED HAVING A HIGH CONCENTRATION OF TIN, IN THE RANGE FROM ABOUT 20 TO ABOUT 35% BY WEIGHT, AND A HIGH CONCENTRATION OF SULFUR, WITHIN THE RANGE FROM ABOUT 10 TO ABOUT 25% SULFUR, COMPRISING AN ORGANOTIN ALPHA- OR BETA-MERCAPTO CARBOXYLIC ACID ESTER AND AN ORGANOTIN SULFIDE. POLYVINYL CHLORIDE RESIN COMPOSITION ARE ALSO PROVIDED CONTAINING THESE STABLIZIERS.

Stats 3,632,538 STABILIZER COMPOSITION CONTAINING MORE THAN 20% TIN ANDRESIN COMPOSITIONS CONTAINING THE SAME Otto S. Kauder, Jamaica, N.Y.,assignor to Argus Chemical Corporation, Brooklyn, N.Y. No Drawing. FiledMay 3, 1967, Ser. No. 635,658 Int. Cl. C08f 45/62 U.S. Cl. 260-23 X 17Claims ABSTRACT OF THE DISCLOSURE This invention relates to a stabilizercomposition for polyvinyl chloride resins and to polyvinyl chlorideresin compositions having improved resistance to deterioration at 350 F.and more particularly, to a stabilizer composition comprising anorganotin mercapto carboxylic acid ester and an organotin sulfide havinga high concentration of tin, and to polyvinyl chloride resincompositions containing such stabilizers.

The stabilizing effectiveness of organotin stabilizers for polyvinylchloride resins is generally associated with organotin groups, tincontent, and, to some degree, sulfur content. The higher the relativeproportion of these, the more effective the organotin compound usuallyis as a stabilizer. However, there are exceptions to the rule that makeprediction fallible.

The organotin sulfides, for example, offer the highest tin and sulfurcontents per organotin group, and yet they are not the best stabilizers,and have never found a place as a commercial stabilizer. Despite theirconsiderably lower tin and sulfur contents, the most effective organotinstabilizers presently in use, and the recognized standard for judgingother organotin stabilizers, are the organotin mercapto carboxylic acidesters. The great majority of these materials, and certainly all of themost commonly used commercial products, are either liquid at roomtemperatures or are low-melting solids. The addition of even a smallproportion of a liquid stabilizing additive has unfavorable effects onthe heat distortion temperature and the impact strength of polyvinylchloride resins. As a result, it is diflicult to provide a high degreeof chemical stability and a high degree of structural stability,problems which generally go hand in hand when rigid resins are subjectedto high temperature conditions. To attain both of these goals, it isnecessary to use as small an amount of the stabilizer as possible, sothat the structural strength of the resin is least affected.

The use of the organotin mercapto carboxylic acid esters as stabilizersfor polyvinyl chloride resins is well known, and is generally set forthin such early patents as U.S. Pats. Nos. 2,753,325 to Leistner et al.,issued June 26, 1956, 2,641,596 to Leistner et al., issued June 9, 1953,and 2,648,650 to Weinberg et al., issued Aug. 11, 1953.

The organotin sulfides are described in U.S. Pat. No. 2,746,946 toWeinberg et al., dated May 22, 1956. Polymeric organotin sulfides havinga high proportion of tin and sulfur by weight have also been suggested.Examples of such materials are given in U.S. Pat. No. 3,021,302 to Frey,dated Feb. 13, 1962, which discloses polymeric condensation products ofhydrocarbon stannonic acid, hydrocarbon thiostannonic acid andco-condensation products of these materials. However, all of thesematerials have suffered from one or another failing, which until now hasprevented their coming into general commercial use.

Similar disclosures of polymeric organotin compounds, which generallyinclude a chain of tin atoms connected through oxygen or sulfur atoms,are set out in U.S. Pats. Nos. 2,597,920, dated Apr. 15, 1962;2,626,953, dated Jan. 27, 1953; 2,628,211, dated Feb. 10, 1953;2,746,946, dated May 22, 1956; 3,184,430, dated May 18, 1956; and2,938,013, dated May 24, 1960.

U.S. Pat. No. 2,809,956, dated Oct. 15, 1957, discloses polymericorganotin compounds which include rmercapto ester groups attached totin, having the general formula:

wherein SX can be a mercapto; mercapto alcohol or ester; or mercaptoacid ester group. These compounds, however, have been found not to be aseffective stabilizers as the monomeric organotin mercapto acid esters,such as dibutyltin bis(isooctyl thioglycolate).

U.S. Pats. Nos. 3,078,390, 3,196,129 and 3,217,004 describe a series ofthioacetal and thioketal organotin carboxylate salt stabilizers whichcan be prepared in situ by the reaction of thioacetal and thioketalcarboxylic acids with dihydrocarbontin oxides or sulfides or thecorresponding monohydrocarbonor trihydrocarbon compounds.

According to the present invention, a particularly effective polyvinylchloride resin stabilizer composition is provided having a relativelyhigh concentration of tin, within the range from about 20 to about 35%Sn, and a relatively high concentration of sulfur, within the range fromabout 10 to about 25% S, and comprising (a) an organotin 06- orfi-mercapto carboxylic acid ester, and (b) an organotin sulfide.

The organotin sulfides useful in this combination each contain groupslinked to tin only through carbon, and a sulfide sulfur group, fl,wherein the sulfide sulfur valences are linked to the same tin atom orto dilferent tin atoms. Each compound contains per tin atom one or twohydrocarbon or heterocyclic groups linked to tin through carbon. Forbest results, and to obtain a synergistic stabilizing effectiveness, atleast one of the compounds of the combination of this invention shouldcontain only one hydrocarbon group per tin atom, linked to tin through acarbon atom. This combination generally improves the initial color of aresin composition during heating, i.e., during the first thirty minutesof a heat test, and can also improve the long-term stability beforefinal charring.

One type of the organotin sulfides useful in this invention can bedefined by the formula:

wherein R is a hydrocarbon group linked to tin through carbon, andcontaining from one to about eight carbon atoms. The atomic ratio ofsulfur to tin is 1:1.

Another group of organotin sulfides of this invention are polymers whichcan be illustrated by the formulae 3 in which each tin atom is linked tothree sulfur atoms and each sulfur is linked to two tin atoms, and x isa number from one to about 100.

Another type has the recurring group where n is the number of units inthe chain, and ranges up to 100 and more.

Another way of defining the R SnS type is:

R s s/R is R S R The Rs are as defined above. The above formulae are notintended to limit the structure of the compound in any way. Thestructures can be straight chain, branched chain, cyclic, or anycombination thereof.

The R hydrocarbon groups in the above formulae can be selected fromamong alkyl, aryl, cycloalkyl, alkyl cycloalkyl, cycloalkylalkyl, andarylalkyl having from one to eight carbon atoms.

The preferred R groups are alkyl groups having from four to eight carbonatoms.

The Organotin sulfides used in this invention are well known to the artand can be prepared by a number of procedures described in earlierreferences which are known to the art. For example, hydrogen sulfide canbe bubbled at about C. into a slurry of hydrocarbontin oxide in water oran organic solvent (such as methanol, acetone, or toluene). Theinsoluble oxide is converted to a solution or dispersion of the sulfideand the reaction is terminated when the entire system is liquefied. 40

Another useful technique is the displacement of hydrocarbontin halide(e.g. Bu SCl by an aqueous alkali metal sulfide or ammonium sulfide.Hydrocarbontin sulfides also can be prepared from the interaction ofhydrocarbontin halide with other sulfur compounds than sulfides, such assodium thiosulfite and ammonium polysulfide. These reactions provideunstable intermediates that decompose to the hydrocarbontin sulfide plusanother product characteristic of the particular starting materials,e.g. alkali metal sulfide or free sulfur.

All the above preparative methods can be summarized r in thetransformations below, where the n-butyltin compounds shown arerepresentative of the entire class of organotin compounds:

Bu sncl Nags Btnsns u NaCl nuzsns n ZNaCl NaHSO Bu SnCI NHnzS,%(BugSnS)n 2NHlo1 2s When these preparations are carried out in anaqueous medium, a small proportion of the sulfur atoms in thehydrocarbontin sulfides are replaced by oxygen atoms, resulting insulfur-deficient products having average compositions represented by theempirical formulae and ((RS S,.O x,) where p is at least 0.85 and r isat least 1.5.

In the stabilizer composition of this invention these sulfides are fullyas effective as the pure oxygen-free sulfides, and wherever Organotinsulfides are mentioned the term is intended to include both the purecompounds and the sulfur-deficient preparations.

There are many other procedures for the preparation of these compounds.The above list of procedures is not intended to be exhaustive. Organotinsulfides prepared by any other procedure would also be useful in thepresent combination.

The R groups linked to tin through carbon can, for example, be methyl,ethyl, propyl, isopropyl, n-butyl, isobutyl, tert-butyl, sec-butyl,amyl, hexyl, octyl, 2-ethylhexyl, isooctyl, phenyl, benzyl, cumyl,tolyl, xylyl, cyclohexyl, and cyclopentyl.

Preferred examples of Organotin sulfides are dipropy1- tin sulfide,dibutyltin sulfide, butyltin sesquisulfide (x from 1 to or higher),di-n-pentyltin sulfide, hexyltin sesquisulfide, dihexyltin sulfide,isooctyltin sesquisulfide, di-2-ethylhexyltin sulfide, heptyltinsesquisulfide, di (isobutyl)tin sulfide, n-octyltin sesquisulfide,di-(n-octyl tin) sulfide and sec-butyltin sesquisulfide propyltinsesquisulfide, dimethyltin sulfide, isoamyltin sesquisulfide, di-(isoamyl)tin sulfide, diisohexyltin sulfide, 2-ethylhexyltinsesquisulfide, 2-ethyl butyltin sulfide.

The above compounds can have any degree of polymerization falling withinthe above formula.

The Organotin mercapto acid esters can be monomeric or polymeric, butpreferably monomeric. The monomers can be defined as Organotin compoundshaving organic radicals linked to tin only through carbon and sulfur,and have the general formula:

The SZ -COOR" group is derived from an aor fi-mercapto carboxylic acidester.

n is an integer from one to two.

m is the number of COOR" groups and is an integer from one to four.

R" is an organic group derived from a monohydric or polyhydric alcoholhaving from one to about four hydroxyl groups and from about one toabout fifteen carbon atoms. If there is more than one COOR" group, theR" radicals can be the same or different.

R is a hydrocarbon radical having from about one to about eight carbonatoms, preferably from four to eight, and includes the groups definedabove for R.

Z is a bivalent alkylene radical carrying the S and COOR groups, and inaddition can contain free carboxylic acid groups, carboxylic acid saltgroups and mercapto groups. The Z radical has from one to about fivecarbon atoms.

The SZ --(COOR") groups are derived from monoor poly uor ,B-mercaptocarboxylic acid esters by removal of the hydrogen atom of the mercaptogroup. These include the esters of aliphatic acids which contain atleast one mercapto group, such as, for example, esters of mercaptoaceticacid, 04- and p-mercaptopropionic acid, aand B-marcaptobutyric acid andaand B-mercaptovaleric acid, thiomalic acid, aand B-mercaptoglutaricacid, mercaptomalonic acid, atand ,B-mercaptoadipic acid and oaandfl-mercaptopimelic acid.

R" is an organic group derived from a monohydric or polyhydric alcoholof the formula R(OH) where 11 is an integer from one to about four, butis preferably one or two. Thus, R can be alkyl, alkylene, alkenyl, aryl,arylene, mixed alkyl-aryl, mixed aryl-alkyl, cycloaliphatic andheterocyclic, and can contain from about one to about fifteen carbonatoms, and can also contain ester groups, alkoxy groups, hydroxylgroups, halogen atoms and other inert substituents. Preferably, R" isderived from a monohydric alcohol containing from one to about fifteencarbon atoms, such as methyl, ethyl,

propyl, s-butyl, n-butyl, t-butyl, isobutyl, octyl, isoctyl, 2ethylhexyl, 2 octyl, decyl, lauryl, cyclic monohydric alcohols, such ascyclopropanol, 2,2 dimethyl l cyclopropanol, cyclobutanol, 2 phenyl 1cyclobutanol, cyclopentanol, cyclopentenol, cyclohexanol, cyclohexenol,2-methyl-, 3 methyl-, and 4-methyl-cyclohexanol, 2-pheny1 cyclohexanol,3,3,5 trimethyl cyclohexanol, cycloheptanol, 12 methyl-, 3 methyland 4methyl cycloheptanol, cyclooctanol, cyclononanol, cyclodecanol,cyclododecanol, or from a dihydric alcohol such as glycols containingfrom two to about fifteen carbon atoms, including ethylene glycol,propylene glycol, diethylene glycol, dipropylene glycol, tetramethyleneglycol, neopentyl glycol and decamethylene glycol, 2,2,4 trimethylpentane-diol, 2,2,4,4 tetramethyl cyclobutanediol, cyclohexane 1,4dimethanol, and polyols such as glycerine, triethylol propane, mannitol,sorbitol, erythritol, dipentaerythritol, pentaerythritol, andtrimethylol propane.

It is not necessary for the alcohol R(OH) to be a single, pure compound.Many of the commercially available and inexpensive alcohol mixtures aresuitable and advantageous. The branched-chain primary alcohols made bythe x0 process and known as isooctyl, isodecyl and isotridecyl alcoholsare mixtures of isomers, but can be used as if they were singlecompounds. Other alcohol mixtures that can be used include mixedhomologous primary alcohols arising from oxidation of the reactionproduct of ethylene with triethyl aluminum, isomers and homologoussecondary alcohols from the hydration of linear C to C olefins or theoxidation of linear C to C parafiins, isomers and homologousstraight-chain and methyl-branched primary alcohols resulting from theapplication to the 0x0 process to C to C linear alpha-olefins,homologous mixtures of reaction products from ethylene oxide withalcohols, phenols or carboxylic acids of the proper carbon content andthe like.

These mercapto acid esters, where not known, can be readily prepared byreaction of the mercaptocarboxylic acid esters with the correspondingorganotin oxide or chloride. For a more complete explanation of theprocess for making, and for additional examples of these diorganotinmercapto ester compounds, see US. Pats. Nos. 2,648,650 to Weinberg etal., 2,641,596 and 2,752,325 to Leistner, and 3,115,509 to Mack, andCanadian Pat. No. 649,989 to Mack.

The organotin mercapto acid esters containing two different mercaptoacid ester groups can be prepared by reacting the desired organotinoxide or chloride with a mixture of the mercapto acid esters, or byheating the two diflerent organotin esters together.

The following organotin thioesters are typical of those coming Withinthe invention:

- n-octyltin sesquisulfide+di-n-propyltin bis(2-ethylhexyl Iri-propyltin sesquisulfide+dicyclohexyltin bis(cyclohexyl ii-n-butyltinsulfide+n-butyltin -tris(2-ethoxyethy1 alpha- L-butyltinsesquisulfide+di-2-ethylhexyltin bis methyl 9 Specific combinations oforganotin sulfides with organotin mercapto carboxylic esters that can beused according 1 i to this invention include the following:

. ii-n-octyltin sulfide+n octyltin tris (isooctyl thioglycolate)n-octyltin sesquisulfidej t-n-octyltin tris(isoocty1.

thioglycolate) 1 1 I 1 n-butyltin: sesquisulfide+di-n-butyltinbis(isooctylthioglycolate) :licyclohexyltin sulfide+di-n-butyltinbis(isooctyl t i g yw a el r r r :yclohexyltin 'sesquisulfidef+din-octyltinbis(isooctyl thioglycolate) thioglycolate) ii-2ethylhexyltinsulfide-i-di n-butyltin bis(2-ethylbutyl thioglycolate)mercaptopropionate) ii-isobutyltin sulfideq-di-isobutyltinbis(tetrahydrofurfuryl beta-mercaptopropionate) t i y a e) phenyltinsesquisulfide+phenyltintris(phenoxyethyl thioglycolate) zthyltinsesquisulfide+di n-butyltin bis(isooctyl 40 thioglycolate) liphenyltinsulfide-l-ethyltin tris(2-ethylhexanoyloxyethyl thioglycolate).sopropyltin sesquisulfide+di-n-butyltin bis(2,2-dimethylpentylthioglycolate) .soamyltin sesquisulfide+di-n-pr0pyltin bis(2-octylalphamercaptopropionate) i-butyltin sesquisulfide+di-n-butyltin4,4-isopropylidene di(cyclohexyl thioglycolate) li-n-butyltinsulfide-l-n-butyltin glyceryl tri(thioglycolate) The invention isapplicable to any polyvinyl chloride 'esin. The term polyvinyl chlorideas used herein is nclusive of any polymer formed at least in part of the1nd having a chlorine content in excess of 40%. In this group, the Xgroups can each be either hydrogen or :hlorine. In polyvinyl chloridehomopolymers, each of the K groups is hydrogen. Thus, the term includesnot only polyvinyl chloride homopolymers but also after-chlori- (i5lated polyvinyl chlorides such as those disclosed in 3ritish Pat. No.893,288 and also copolymers of vinyl :hloride in a major proportion andother copolymerizable nonomers in a minor proportion, such as copolymersof inyl chloride and vinyl acetate, copolymers of vinyl :hloride withmaleic or fumaric acids or esters, and co- )olymers of vinyl chloridewith styrene, propylene, and athylene. The invention also is applicableto mixtures of molyvinyl chloride in a major proportion with other.ynthetic resins such as chlorinated polyethylene or a copolymer ofacrylonitrile, butadiene and styrene. Among the polyvinyl chlorideswhich can be stabilized are the uniaxially-stretch orientedpolyvinylchlorides described in U.S. Pat. No. 2,984,593 to Isaksem etal., that is,

syndiotactic polyvinyl chloride, as well as atactic and isotacticpolyvinyl chlorides. The stabilizing combinations of this stabilizersfor both 'plasticized and unplasticized polyvinyl chloride resins. Whenplasticizers are to be employed, they may be incorporated into thepolyvinyl chloride resins in accordance 'withconventional means. Theconventional plasticizers can be used, such as dioctyl phthalate,dioctyl sebacate and tricresyl phosphate. Where a plasticizer isemployed, itcan be used in anamount within the range from 0 to parts byweight of the resin.

invention, both with andwithout supplementary stabilizers, are excellentParticularly useful plasticizersare theepoxy higher p esters having fromabout twenty to about one hundred fifty carbon atoms. Such 'esterswillinitially have had unsaturation in the alcohol or acid portionofthemolecule,which is taken up by the formation of the epoxy group.

' Typical'unsa'turated acids are oleic, linoleic, linolenic,

erucic, ricinoleic and .brassidic acids, and these may be esterifiedwith organic monohydric or polyhydric alcohols, the total number ofcarbon atoms ofthe acid and the alcohol being within. the range stated.Typical monohydric alcohols include butyl alcohol, 2-ethylhexyl alcohol,lauryl'alcohol, isooctyl alcohol, stearylalcohol, and oleyl alcohol. Theoctyl alcohols are preferred. Typical polyhydric alcohols includepentaerythritol, glycerol, ethylene glycol, I 1,2-propylene' glycol,1,4-butylene glycol, neopentyl glycol, ricinoleyl alcohol, erythritol,mannitol and 5 sorbitol- Glycerol is preferred. These alcohols may befully or partially esterified with the epoxidized acid..Also useful arethe epoxidized mixtures of higher fatty acid mestersfound innaturally-0ccurring oils such as epoxidized soybean oihepoxidized oliveoil, epoxidized cottonseed oil, epoxidized tall oil fatty acid esters,epoxidized soybean oil is preferred. 1

The alcohol can contain the epoxy group and have a long or short chain,and the acid can have a short or long chain, such as epoxy stearylacetate, epoxy stearyl stearate, glycidyl stearate, and polymerizedglycidyl methacrylate.

A small amount, usually not more than 1.5%, of a parting agent orlubricant, also can be included. Typical parting agents are the higheraliphatic acids, and salts having twelve to twenty-four carbon atoms,such as stearic acid, lauric acid, palmitic acid and myristic acid,lithium stearate and calcium palmitate, mineral lubricating oils,polyvinyl stearate, polyethylene and parafiin Wax.

Impact modifiers, for improving the toughness or impact-resistance ofunplasticized resins, can also be added to the resin compositionsstabilized by the present invention in minor amounts of usually not morethan 10%. Examples of such impact modifiers include chlorinatedpolyethylene, ABS polymers, and polyacrylate-butadiene graft copolymers.

The stabilizer composition of the invention, including the organotinmercapto acid ester and organotin sulfide, is employed in an amountsuflicient to impart the desired resistance to heat deterioration atWorking temperatures of 350 F. and above. The longer the time and themore rigorous the conditions to which the resin will be subjected duringworking and mixing, the greater will be the amount required. Generally,as little as 0.25% total of the stabilizer composition by weight of theresin, will improve resistance to heat deterioration.

There is no critical upper limit on the amount, but amounts above about15% by weight of the resin do not give an increase in stabilizingeffectiveness commensurate with the additional stabilizer employed.Preferably, the

linseed oil and epoxidized tallow. Of these, epoxidized amount is fromabout 0.5 to about by weight of the resin.

The proportion of the organotin rnercapto acid ester and of theorganotin sulfide is suflicient to give a sulfur content in thecomposition within the range from about 12 to about 125%, and a tincontent within the range from about 20 to 35%. For best results anoverall sulfur content from about 22% to about 30% by weight of thestabilizer composition is preferred. Accordingly, the proportions byweight of organotin mercapto ester to organotin sulfide will usually bewithin the range of 20:1 to 1:2 and preferably within the range of 9:1to 1:1.

The stabilizer combination of the invention is extremely eifective whenused alone, but it can be employed together with other polyvinylchloride resin stabilizers, if special effects are desired. Thestabilizer combination of the invention in this event will be the majorstabilizer, and the additional stabilizer will supplement thestabilizing action of the former, the amount of the stabilizercombination being within the range from about 0.25 to about 15 partsEXAMPLE 1 A series of rigid or nonplasticized formulations was preparedhaving the following composition.

Stabilizer 100. As shown in Table. I.

The stabilizer concentrations used in each sample of resin testedcontained the amount of tin, shown in Table I below per 100 parts ofresin.

The stabilizer components were first mixed together in the proportionsindicated in Table I below, and were then mixed in the resin on a tworoll mill to form a homogeneous sheet, and sheeted off. Strips were cutoff from the sheet and heated in an oven at 375 F. for two hours todetermine heat stability. Pieces of each strip were removed at minuteintervals and aflixed to cards to show the progressive heatdeterioration. The appearance of the by weight per 1100 parts of theresin, and the additional samples 18 reported in Table I below.

TABLE I Examples Control A Amt. Example 1 Amt. Example 2 Amt. Control BAmt.

Stabilizer composition .Monobutyltin tris (iso- Monobutyltin tris(iso-Monobutyltin tiis(isopctyl thioglycolate) 2. 7 oetyl thioglycolate) 1.90 octyl thioglycolate) 4- 1.

Dibutyltin sulfide 0. 3 D butyltin sulfide 0. 5 Dibutyltin sulfide 1.0Tin tg.) i). 410 Tin (g) 0.422 T111 (g.) 0. 430 Tin(g.) o, 446

Time (min) Color Color Color C l Initial Colorless Colorless ColorlessColorless.

ery slight yellow tint Very slight yellow tint. Yellow. Slightyellowtint Slight yellow tint Do stabilizer being in an amount of from about0.05 to about 10 parts per 100 parts of the resin.

Among the additional metallic stabilizers are included other organotincompounds, polyvalent metal salts of medium and of high molecular weightfatty acids and phenols, with metals such as calcium, tin, cadmium,barium, zinc, magnesium, and strontium. The non-metallic stabilizersinclude phosphites, epoxy compounds, and the like. Epoxy compounds areespecially useful, and typical compounds are described in US. Pat. No.2,997,454.

Generally, the stabilizer composition of this invention can be preparedby mixing the organotin mercapto acid ester with the organotin sulfide,either alone, or with any liquid lubricant or plasticizer to be added tothe resin composition with the stabilizer.

The preparation of the polyvinyl chloride resin composition is easilyaccomplished by conventional procedures. The selected stabilizercombination is formed as above, and then is blended with the polyvinylchloride resin, or alternatively, the components are blendedindividually in the resin, using, for instance, a two or three rollmill, at a temperature at which the mix is fluid and thorough blendingfacilitated, milling the resin composition including any plasticizer atfrom 250 to 375 F. for a time suflicient to form a homogeneous mass,five minutes, usually. After the mass is uniform, it is sheeted off inthe usual way.

For the commercial processing of rigid polyvinyl chloride, thestabilizer is conveniently mixed with all or a portion of the polymer tobe stabilized with vigorous agitation under such conditions of time andtemperature that the stabilizer is sufficiently imbibed by the polymerto produce a dry, free-flowing powder. The well-known Henschel mixer iswell suited tothis procedure.

The following examples in the opinion of the inventor representpreferred embodiments of this invention:

Very1 light yellow. 0 Light yellow. Charred yellow.

The results clearly indicate the improved efiectiveness obtainable bycombining dibutyltin sulfide, the highly concentrated organotincompound, with monobutyltin tris (isooctyl thioglycolate). Thestabilizer combinations of this invention, 2.2 parts per parts resin, asexemplified by Example 1, and 1.85 parts per 100 parts resin, asexemplified by Example 2, provided a very lightly colored, clearcomposition after 30 minutes of heating at 375 F. that was no morediscolored than Control A, containing monobutyltin tris(isooctylthioglycol-ate) in a higher total amount of stabilizer, i.e. 2.7 partsby weight per 100 parts resin, after 15 minutes of heating. The degreeof discoloration shown by Control A after 30 minutes was maintained bythe sample of Example 1 for 45 minutes and by the sample of Example 2for 60 minutes of heating. Thus, the stabilizer compositions of thisinvention considerably extend the processing period for resins beforeharmful discoloration appears. Control B, containing dibutyltin sulfidealone, showed undesirable initial and early properties, i.e. theformation of a yellow discoloration in the resin within only 15 minutesafter heating had begun.

EXAMPLES 3 THROUGH 5 A series of rigid nonplasticized resin formulationswas prepared having the following composition:

Ingredients: Parts by weight Polyvinyl chloride homopolymer (Diamond 40)100. Stabilizer combination As shown in Table II.

The same procedure was followed in preparing and test ing thecompositions as in Example 1 and the appearance of the samples isreported in Table II below. Each resin sample contained the same totalamount of stabilizer, 2.2 parts by weight per hundred parts resin.

TABLE II Examples Control Amt. Example 3 Amt. Example a Amt. ExampleAmt. Control D Amt.

Stabilizer composition Monobutyltin tris Monobutyltin tris Monobutyltintris Monobut-yltin tris (isooctyl hio- (isooctylthio- (isooctylthio-(isooctylthioglycolate 1. 76 glycolate) 1.605 glycolate) 1. 425glycolate) 2. 2 Dibutyltin sulfide 0. 44 Dibutyltin sulfide. 0. 595Dibutyltin sulfide. 0. 775 Dibutyltin sulfide- 2. 2 'Iin (g) 0. 334 Tin(g) 0.465 Tin (g) 0.520 Tin (g.) 0. 564 Tin (g.) 0. 980

Time (min) Color Color Color Color Color lnitial- Colorless orlessColorless Colorless. [5... y slight yellow tint. Very slight yellow tintYellow 30 do..- Do. 45. Yellow ery light yellow or y ligh Do. 30 Darkyellow 0 do Dark yellow. 75- Black Light yellow ight y Do. 3U YellowYellow Do. 105 Char ed yellow Charred yellow Do. I20 Black BrownYellow-brown.

The results clearly indicate that when used at equal 20 The results ofTable III clearly indicate the improved total concentrations by weight,all of the claimed stabilizer :ombinations, monobutyltin tris(isooctylthioglycolate) and dibutyltin sulfide, inhibit the deterioration of theresin upon heating at 375 F. for a period of time substantially longerthan either component alone and thus increase processing time before aharmful discoloration appears. Control C acquires a very light yellowdiscoloration with- .n 15 minutes of heating but Examples 3, 4 and 5maintain 1 less discolored appearance for 45 minutes of heating. Inaddition, the resin compositions Examples 3, 4 and 5 :ontaining thenovel combination of stabilizers maintain more than a lightdiscoloration even after 90 minutes of heating at 375 F. Contrarily,Control C, the composiiion containing the monobutyltin tris(isooctylthioglycolate), acquires a dark discoloration after 60 minutes and sblack after 75 minutes of heating. Control D, although I does not turnblack until after two hours of heating, :lisclors immediately, i.e.after minutes of heating, to a. yellow discoloration and maintains thisundesirable color luring the term of heating, acquiring a darkerdiscoloralion after 60 minutes.

EXAMPLES 6 THROUGH 8 Another series of rigid resin formulations wasprepared having the following composition:

Ingredients: Parts by weight Polyvinyl chloride homopolymer (Diamond 40)100. Isooctyl epoxy stearate 3. Stabilizer combination As shown in TableIII.

The same procedure was followed in preparing and Zesting thecompositions as in Example 2 and the appearance of the samples arereported in Table III below. Each resin sample contained the same totalamount of stabilizer, 1.5 parts by weight per hundred parts resin.

effectiveness obtained by combining dibutyltin sulfide, the highlyconcentrated organotin compound, with monobutyltin tris(isooctylthioglycolate) even at the low total proportions by weight in thepresent example, i.e. 1.5 parts per hundred parts resin. The samplescontaining the combination of the present invention, Examples 6, 7 and8, inhibit the deterioration of the resin upon heating at 375 F. for aperiod of time substantially longer than either component alone. ControlE turned a very light yellow within 15 minutes of heating, but Examples6, 7 and 8 maintained a less discolored appearance until 30 minutes ofheating had elapsed.

In addition, the resin compositions of Examples 6, 7 and 8 containingthe novel combination of stabilizers maintained no more than a lightdiscoloration even after minutes of heating. Contrarily, Control E, thecomposition containing the monobutyltin tris(isooctyl thioglycolate)alone acquired a dark discoloration after 30 minutes of heating andturned black after minutes of heating. Control F, although it does notturn black until after two hours of heating, discolors immediately, i.e.after 15 minutes of heating to a yellow discoloration. It maintains thisundesirable color during the term of heating and becomes a darkerdiscoloration after 75 minutes.

EXAMPLES 9 THROUGH 11 A series of rigid nonplasticized formulations wasprepared having the following composition:

Parts by weight TABLE III Examples Control E Amt. Example Amt.

Example 7 Amt. ExampleS Amt. ControlF Amt.

Stabilizer composition Monobutyltin tris(isooetyl thioglycolate)Dibutyltin sulfide Monobutyltin tris(isooctyl Monobutyltin tris(isooctylthioglycolate) Dibutyltin sulfide 0. 405

Monobutyltin tris(isooetyl thioglycolate) Dibntyltin sulfide DibutyltlnO. 53 sulfide thioglycolate) Iime minutes) C olor C olor C olor ColorColor Colorless Very slight yell Very light yellow do Light yellow Greeiish yellow Black C olorless Very slight yell Very light yellow. Ligg;yellow Colorless Colorless.

Yellow.

Do. Dark yellow.

TABLE IV Examples Control G Amt. Example 9 Amt. Example 10 Amt. Example11 Amt. Control H Amt.

Stabilizer composition Dibutyltin bls- Dibutyltin bis Dibutyltlnbisifisooctylthio- (isooctylthlo- (isooetylthio- Dlbutyltinbisglycolate) 2.52 glycolate) 2.07 glycolate) 1. 48

tisooctylthio- Butyltin sesqui- Butyltin sesqui- Butyltin sesqul-Butyltlnsesqul- Tim glycolate) 2.96 sulfide 0.15 sulfide 0.30 sulfide0.5 sulfide 1.0

e (min) Color Color Color Color Colorless Colorless. 15 Light yellow.

Very1 slight yellow tin Light tan.

do o. o Tan. Very light yellow- Very light yellow Very light yellow...Dark tan. do do o do Brown.

90 Light yellow with brown do do Light tan Black.

corners 105 Light yellow with brown Light yellow with brown Light yellowdo e ges. corners. 120 Yellow with brown Light yellow with brown Lightyellow with brown Tan edges. edges. corners.

The advantages of using the combinations of this in- Profiles vention inExamples 9, 10 and 11 are clearly shown over the use of the componentsalone in Controls G and H when used at equal parts of tin per 100 partsof resin. As shown in Control G, the dibutyltin bis(isooctylthioglycolate), acquires a very light yellow discoloration within thefirst 15 minutes of heating. Examples 9 through 11 maintain a lightercolor for more than minutes and do not show the same discoloration untilafter minutes of heating have elapsed. This shows that the combinationof this invention is four times as effective in stabilizing the resin atequal parts of tin. In addition, the total amount of stabilizer added issubstantially lower in Examples 9 through 11 as compared to Control G.Control H turns a light yellow color Within 15 minutes after heating andExamples 9 through 11 do not become this discolored until after 90minutes of heating.

The stabilizer compostions of this invention are advantageously used inresins formed into many useful structural members including extrudedpolyvinyl chloride pipe useful for water, brine, crude petroleum,gasoline, natural and manufactured fuel gas, and domestic and industrialwastes; fiat and corrugated profiles for the construction industry, andblow-molded bottles, Typical formulations are as follows:

Pipe

Composition: Parts by weight Medium mol. wt. polyvinyl chloridehomopolymer ('K=55) 100 ABS polymer 10 Calcium stearate 1 Dibutyltinsulfide 0.5 n-Butyltin bis(isooctyl thioglycolate) 0.9 Pigment Asdesired Parisons for blow-molding bottles Composition: Parts by weightMedium mol. wt. polyvinyl chloride homopolymer (K 55) 100 Styrenelbutadiene methyl methacrylate polymer 1O Stearic acid 0.5 n-Butyltinsesquisulfide 0.5 Di-n-butyltin bis(n-dodecyl thioglycolate) 1.1 Bluedye 00005-0002 Food-grade bottles Composition: Parts by weight Mediummol. wt. polyvinyl chloride homopolymer lK=55) 100 ABS polymer l0n-Octyltin sesquisulfide 0.5

Di-n-octyltin bis(isooctyl thioglycolate) 0.95 Di-n-octyltin oxide 0.05

Composition: Parts by weight High mol. wt. polyvinyl chloridehomopolymer (K=70) Chlorinated polyethylene (31% Cl) 15 Isooctylepoxystearate 2 Di-n-octyltin sulfide 0.75 n-Butyltin tris(isooctylthioglycolate) 1.0 Magnesium stearate 0.25

These formulations each contain sufiicient stabilizer in accordance withthe invention to be processed at elevated temperatures into the desiredshapes without deleterious discoloration or embrittlement.

Having regard for the foregoing disclosure, the following is claimed asthe inventive and patentable embodiments thereof:

1. A stabilizer composition for improving the resistance todeterioration of polyvinyl chloride resins when heated at 350 F.,consisting essentially of an organotin alphaor beta-mercapto carboxylicacid ester having the formula R,,Sn-ESZ(COOR)m"] wherein R is an alkylradical linked to tin through carbon and having from one to about eightcarbon atoms, Z is a bivalent alkylene radical having from one to abouttwo carbon atoms, and carrying the S- and COOR" groups, and R is anorganic group derived from a monohydric or polyhydric alcohol havingfrom one to about two hydroxyl groups and from one to about fifteencarbon atoms, In is an integer from 1 to 2, and n is an integer from 1to 2, the SZ(COOR") group being derived from an alphaorbeta-mercaptocarboxylic acid ester; and an organotin sulfide having theformula R SnS, in which R is alkyl linked to tin through carbon and hasfrom one to about eight carbon atoms, the organotin compounds togethercomprising an amount of tin within the range from about 20 to about 35%by weight, and an amount of sulfur within the range from about 10 toabout 35% by weight.

2. A stabilizer composition in accordance with claim 1, in which theorganotin mercaptocarboxylic acid ester is an organotin thioglycolate.

3. A stabilizer composition in accordance with claim 1, in which theorganotin sulfide is dibutyl tin sulfide and the organotinmercaptocarboxylic acid ester is monobutyl tin or monooctyl tin tris(isooctyl thioglycolate).

4. A stabilizer composition according to claim 1, in which n is 1.

5. A stabilizer composition according to claim 4, in which the organotinmercaptocarboxylic acid ester is monobutyl tin tris(isooctylthioglycolate) and the organotin sulfide is dibutyl tin sulfide.

' 6. A stabilizer composition according to claim 4, in

vhich the organotin' mercaptocarboXy-lic acid ester is.

nonobutyl tin tris(isooctyl thioglycolate and the organo- 7. Astabilizer composition according to;claim 4, in. vhich the organotinmercaptocarboxylic acid ester is nonobutyl tin. tris(isooctylthioglycolate).

'8. A stabilizer composition according'to claim 4, 'in' I vhich theorganotin sulfide is dibutyl tin sulfide.

9; A polyvinyl chloride resin composition having an :nhanced resistanceto deterioration when heated at 35 0 I 15. A polyvinyl chloride resincomposition in accord- '.ance with claim 9 including in addition anepoxy compound.

16. A polyvinyl chloride resin composition inaccord-v I ance with claim9 including in addition a plasticizer for v the, resin in an amount inexcess of about 15% by weight.

PK, consisting essentially of a polyvinyl chloride resin I and astabilizer compositionin accordance with claim 1.

10. A'polyvinyl chloride resin composition in accord- I I I tnce withclaim 9 in which the polyvinyl chloride resin is aolyvinyl chloridehomopolymer. I

11. A polyvinyl chloride resin composition in accord.-

mce with claim 9 in which the polyvinyl chloride resin is a copolymerofvinyl chloride andvinyl acetate.

12. A polyvinyl chloride resin composition'in accord;- mce with claim 9in which the amount of stabilizer composition is within the range fromabout O.25% to about 15% by weight of the composition.

13. A polyvinyl chloride resin composition in accordance with claim9includingin addition a polyvalent metal 20 salt of an aliphatic fattyacid. I I I I 14. A polyvinyl chloride resin composition in accord-11166 with claim '9'including in addition an organic phosphite.

' 17., A rigid polyvinyl chloride resin composition ac cordance withclaim .9 comprising; a plasticizer, in an amount up to about 10% byWeight of the composition.

References Cited UNITED STATES PATENTS Leistner 26045.85

DONALD E; CZAIA, Primary Examiner I I I V ,V, .P. HOKE, AssistantExaminer US. Cl. X.R.

252406 R; 260--31.8 R, 45.7 P, 45.75 K

g gg UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION PatentNo.3,632,538 I Dated January 4, 1972 Inventor(s) Otto S. Kauder It iscertified that error appears in the above-identified patent and thatsaid Letters Patent are hereby corrected as shown below:

Column 1, Title, "STABILIZER COMPOSITION CONTAINING line 3 I MORE THAN20% TIN'AND RESIN "COM- Y POSITIONS CONTAINING THE SAME" should be IORGANOIIN STABILIZER' COMPOSITION CONTAINING MORE THAN 20% TIN AND'RESIN COMPOSITIONS CONTAINING THE SAME Column 2, A line 31 "'trihydrocarbon" should be I trihydrocarbontin Column 3, lines'6, "S should be --ISn 15 and 19 Column 3, lines 72 "s should be Sn andli I Column 4, line56 "oror B-mercapto" should be ozand B-mercapto Column 4, line 61"marcaptobutyric" should be I mercaptobutyric Column 5, line 34 "0x0";should be V 'Oxo Column 6, line 49 v 'C H E I Fania "C H gsnr shouldCgI-I -Sn- '(CH2)2".J

I. 0 S 0E 3,632,538 Page 2' Column 11, line 38 "disclors" should bediscolors Column 11, line 49 "3." should be- '3 Column 11, Table m'An'n't. Example" shouldbe Heading Amt. Example 6 Column 15, line-3'"(isooctyl thiogiycolate" shduld be --1 (isooctyl thioglycolate) Signedand sealedi-this day of February 1973.

(SEAL) Attest: l

EDWARD M.FLETCHER,JR.. i v I j RQB ERT GOTTSCHALK Attestlng' Officer ICommissioner of Patents

